In practicing the known resin transfer molding process (RTM process), a catalyzed resin, such as catalyzed epoxy resin, is melted in a heated, gas pressurized pot and supplied through a heated resin supply hose or pipe to a mold for infiltrating a fiber reinforcement positioned in the mold to form a fiber reinforced molded product. The resin supply hose or pipe is comprised of copper line with wrapped heating element. The hose components are fixed at opposite ends to conventional compression fittings that connect to tapped holes on the resin pot and the mold.
The heated resin supply hose previously used has been quite disadvantageous in the RTM injection molding of medium to high viscosity catalyzed epoxy resin wherein residual resin remains in the hose following each injection cycle. As a result, the supply hose must be cleaned with a suitable, environmentally hazardous solvent following each injection cycle in attempt to remove the residual resin, which may be partially or fully cured in the hose. The solvent is pumped through the supply hose to remove as much resin as possible. Despite these attempts to remove residual resin from the supply hose, there is experienced in practice of the RTM process a progressive build-up of residual resin in the supply hose that eventually requires the hose to be scrapped in toto and replaced by a new resin supply hose. Such detrimental resin buildup has been observed to occur in relatively short time, such as in as few as one injection cycle of the RTM process.
An object of the present invention is to provide a heated supply hose and method for supplying molten resin and other molten materials in a molding or other process that overcomes the aforementioned disadvantages.